491
FXUS65 KBYZ 281839
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
1239 PM MDT MON SEP 28 2026
KEY MESSAGES
- A FEW SHOWERS AND THUNDERSTORMS (MAINLY MOUNTAINS AND FAR
SOUTHEAST MT) INTO EARLY THIS EVENING.
- MILD AND MOSTLY DRY WEATHER PATTERN PREVAILS TUESDAY THROUGH THE
WEEKEND.
DISCUSSION
THROUGH NEXT MONDAY...
SATELLITE IMAGERY SHOWS SPLITTING TROF MOVING SLOWLY THRU
WESTERN/CENTRAL MT. 300MB JET DIVERGENCE CONTINUES TO PRODUCE SOME
LIGHT SHOWERS WHICH ARE MOVING WEST-TO-EAST ACROSS SOUTHERN
PORTIONS OF OUR FORECAST AREA. DRYING/CLEARING HAS ALREADY
OCCURRED OVER OUR WEST, BUT GIVEN THE TROF AXIS IS STILL TO OUR
WEST THERE SHOULD BE SOME MAINLY MOUNTAIN SHOWERS DEVELOP IN THE
LATE AFTERNOON AND EARLY EVENING. HIGH RES MODELS SEEM CONSISTENT
HERE. FREEZING LEVELS SUPPORT SNOW SHOWERS ABOVE 11.5KFT, SO THE
HIGHEST PEAKS OF THE BEARTOOTHS COULD SEE A LITTLE WET SNOW. A
POTENTIALLY MORE IMPACTFUL ITEM TO WATCH OVER THE NEXT FEW HOURS
IS WHETHER OR NOT ANY STRONG T-STORMS DEVELOP NEAR THE DAKOTAS
BORDER. MESOANALYSIS SHOWS INCREASING (BUT VERY CAPPED)
INSTABILITY, WITH MLCAPES EXCEEDING 1000 J/KG IN FALLON/CARTER.
HOWEVER, A SHIFT TO MUCH DRIER WEST WINDS IS RAPIDLY APPROACHING
AND THUS, ALL CAMS SHOW STRONGER CONVECTION DEVELOPING EAST OF THE
MONTANA STATE LINE LATER THIS AFTERNOON. IN FACT, SPC'S DAY1
OUTLOOK SHOWS A MARGINAL RISK OF SEVERE T-STORMS OVER THE BLACK
HILLS. ASCENT WITH THE UPSTREAM WAVE CONTINUES THRU 00Z, SO THIS
IS SOMETHING TO WATCH.
DOWNSLOPE GRADIENTS TIGHTEN SOMEWHAT IN OUR WEST TONIGHT, SO LOOK
FOR DEVELOPING BREEZY CONDITIONS ALONG THE WESTERN FOOTHILLS. THIS
WILL TRANSLATE TO BREEZY CONDITIONS TUESDAY WITH TEMPS GETTING
WELL INTO THE 70S.
OTHERWISE, WE ARE ENTERING A DRIER/QUIETER WEATHER PATTERN UNDER
W/NW FLOW ALOFT TOMORROW THRU THE WEEKEND. THERE WILL BE A SERIES
OF WEAK SHORTWAVES TRACKING NEAR THE MT/CANADA BORDER THAT WILL
ALLOW FOR PERIODIC MODEST PUSHES OF COOLER CANADIAN AIR
(WEDNESDAY, THURSDAY, AND FRIDAY INTO SATURDAY). IT IS POSSIBLE
THAT LIGHT PRECIP WILL BE ASSOCIATED WITH SOME OF THESE WEAK
FRONTAL PUSHES, MAINLY NORTH OF THE SOUTHERN FOOTHILLS, AND THIS
IS A SOURCE OF MODEL UNCERTAINTY AT THIS TIME. TEMPERATURES ARE
LIKELY TO FLUCTUATE BETWEEN NEAR NORMAL AND WARMER THAN NORMAL.
OVERWHELMING ENSEMBLE CONSENSUS IS FOR BUILDING HEIGHTS BY THE END
OF THE WEEK AND INTO NEXT WEEK, DUE TO A STRENGTHENING RIDGE
ANCHORED TO OUR WEST. THIS COULD KEEP US PRONE TO PERIODIC
BACKDOOR "COOLING" BUT THE HIGH HEIGHT REGIME DEFINITELY FAVORS
ABOVE NORMAL TEMPS AND DRY CONDITIONS MOVING INTO EARLY NEXT WEEK.
FOR THOSE LOOKING FOR A DOSE OF WINTER AS WE MOVE INTO EARLY
OCTOBER, THAT IS NOT IN THE CARDS YET. THERE IS HIGH CONFIDENCE
FOR ABOVE NORMAL TEMPS AND BELOW NORMAL PRECIP THROUGH THE FIRST
THIRD OF THE MONTH, PER WESTERN CONUS RIDGING. COOLER AIR WILL BE
OVER THE EASTERN HALF OF THE COUNTRY. THE PACIFIC TROPICS REMAIN
QUITE ACTIVE AND SHOULD BE MONITORED AS WELL.
JKL
AVIATION
A BROKEN LINE OF SHOWERS CONTINUES TO MOVE EASTWARD THROUGH
SOUTHERN MONTANA AND NORTHERN WYOMING TODAY. EXPECT THESE SHOWERS
TO GRADUALLY TAPER OFF THROUGH THE AFTERNOON. ADDITIONAL SHOWERS
AND THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING OVER THE
MOUNTAINS (MEDIUM CHANCE) AND OVER FAR EASTERN MONTANA (LOW
CHANCE). SHOULD THUNDERSTORMS DEVELOP OVER FAR EASTERN MONTANA, A
FEW COULD BECOME STRONG WITH GUSTY WINDS, HAIL, AND HEAVY RAIN
BEING THE MAIN THREATS. OTHERWISE, BREEZY WEST TO SOUTH- WESTERLY
WINDS ARE FORECAST AROUND KLVM, K6S0, AND K3HT TONIGHT INTO
TUESDAY. LA
PRELIMINARY POINT TEMP/POPS
TUE WED THU FRI SAT SUN MON
-----------------------------------------------------------
BIL 047/077 049/073 045/068 047/074 049/066 044/068 047/077
00/N 00/U 00/U 01/B 20/B 10/B 00/B
LVM 039/075 043/072 038/071 043/076 043/068 038/071 043/078
10/U 00/U 00/U 01/B 21/U 10/U 00/U
HDN 043/079 046/073 043/070 044/075 047/067 042/070 044/078
00/U 00/U 00/U 01/B 31/B 10/U 00/U
MLS 046/077 049/072 044/066 046/073 049/066 043/067 046/074
00/U 00/U 00/B 00/B 21/B 00/U 00/U
4BQ 047/078 049/073 046/069 048/075 050/066 044/068 047/076
10/U 00/U 00/B 00/B 21/U 00/U 00/U
BHK 046/078 048/072 040/064 042/073 045/066 038/064 042/073
20/U 00/U 00/B 01/B 21/B 00/U 00/U
SHR 040/077 042/072 040/071 042/076 044/067 039/069 042/077
20/U 00/U 11/U 11/U 21/U 10/U 00/U
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
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